1. Technical Field
The present invention relates to an electrophoretic display technique.
2. Related Art
Upon the application of an electric field to a dispersion liquid (also referred to as a “disperse system”) containing electrically-charged particles dispersed in a solvent (a dispersion medium), the particles move (are electrophoresed) in the dispersion medium by the action of the Coulomb force. This phenomenon is called electrophoresis. Electrophoretic displays (EPDs) utilize electrophoresis to display desired information, such as images.
Known EPDs include a plurality of spaces (cells) separated by partitions between a pair of substrates. Each of the cells includes a disperse system containing electrically-charged particles (electrophoretic particles) in a dispersion medium. Such EPDs can be manufactured by filling each of the cells with the disperse system and sealing the opening of each of the cells. The sealing may be performed by a method described in JP-A-5-165064 or JP-T-2005-509690.
In accordance with JP-A-5-165064, the opening of each of the cells is covered with a flexible electrode, and the cells are then sealed while excess dispersion liquid is forced out by applying pressing force to the flexible electrodes.
In accordance with JP-T-2005-509690, the cells are sealed with a sealing composition. The sealing composition contains a thermoplastic elastomer and a solvent or a solvent mixture immiscible with the dispersion liquid and having a lower specific gravity than the dispersion liquid. The sealing composition having a lower specific gravity than the dispersion liquid is separated upward from the dispersion liquid. Hardening of the thermoplastic elastomer in such a state allows the sealing of the cells.
It is important to prevent the incorporation of air (bubbles) into the cells during the enclosure of the dispersion liquid in the cells. In the sealing under mechanically pressing force according to JP-A-5-165064, depending on the amount of dispersion liquid enclosed in the cells, bubbles may be incorporated into the cells.
In accordance with the technique disclosed in JP-T-2005-509690, an insufficient difference in specific gravity between the dispersion liquid and the sealing composition may result in insufficient separation of the sealing composition from the dispersion liquid. This makes the control of the amount of dispersion liquid enclosed in the cells difficult, possibly causing variations in the amount of dispersion liquid.